High sensitivity, supramolecular thin films for sensing of methane

A method has been developed to obtain uniform thin layers of the supramolecule cryptophane A (CrypA) on quartz crystals to produce high-sensitivity gravimetric methane gas sensors. Molecular mechanics and ab initio simulations were used for the first time to calculate the binding energy of methane to CrypA. The results justify the use of CrypA to selectively sense methane amongst a mixture of gases. CrypA molecules were synthesized by an improved 2-step trimerization method and characterized by 1 H-NMR spectroscopy. The response of these sensors to different concentrations of methane was studied. The detection limit of 3ppm (i.e., 0.003%) with a sensitivity of 80mHz/ppm show significant improvement over the prior art.